81 lines
2.1 KiB
Go
81 lines
2.1 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
|
|
// except in compliance with the License. You may obtain a copy of the License at
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
// Unless required by applicable law or agreed to in writing, software distributed under the
|
|
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
|
|
// either express or implied. See the License for the specific language governing permissions
|
|
// and limitations under the License.
|
|
|
|
// +build libstemmer full
|
|
|
|
package stemmer_filter
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"bitbucket.org/tebeka/snowball"
|
|
"github.com/blevesearch/bleve/analysis"
|
|
"github.com/blevesearch/bleve/registry"
|
|
)
|
|
|
|
const Name = "stem"
|
|
|
|
type StemmerFilter struct {
|
|
lang string
|
|
stemmerPool chan *snowball.Stemmer
|
|
}
|
|
|
|
func NewStemmerFilter(lang string) (*StemmerFilter, error) {
|
|
stemmerPool := make(chan *snowball.Stemmer, 4)
|
|
for i := 0; i < 4; i++ {
|
|
stemmer, err := snowball.New(lang)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
stemmerPool <- stemmer
|
|
}
|
|
return &StemmerFilter{
|
|
lang: lang,
|
|
stemmerPool: stemmerPool,
|
|
}, nil
|
|
}
|
|
|
|
func MustNewStemmerFilter(lang string) *StemmerFilter {
|
|
sf, err := NewStemmerFilter(lang)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return sf
|
|
}
|
|
|
|
func (s *StemmerFilter) List() []string {
|
|
return snowball.LangList()
|
|
}
|
|
|
|
func (s *StemmerFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
|
|
for _, token := range input {
|
|
// if it is not a protected keyword, stem it
|
|
if !token.KeyWord {
|
|
stemmer := <-s.stemmerPool
|
|
stemmed := stemmer.Stem(string(token.Term))
|
|
s.stemmerPool <- stemmer
|
|
token.Term = []byte(stemmed)
|
|
}
|
|
}
|
|
return input
|
|
}
|
|
|
|
func StemmerFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
|
|
langVal, ok := config["lang"].(string)
|
|
if !ok {
|
|
return nil, fmt.Errorf("must specify stemmer language")
|
|
}
|
|
lang := langVal
|
|
return NewStemmerFilter(lang)
|
|
}
|
|
|
|
func init() {
|
|
registry.RegisterTokenFilter(Name, StemmerFilterConstructor)
|
|
}
|